The onset of star formation 250 million years after the Big Bang

TL;DR

This paper reports the detection of a galaxy forming stars just 250 million years after the Big Bang, providing insights into the earliest galaxy formation and demonstrating the potential for future observations of such early epochs.

Contribution

First spectroscopic confirmation of a galaxy at redshift 15, revealing star formation occurred 250 million years after the Big Bang, pushing the observational frontier of early universe studies.

Findings

Detected galaxy at redshift 15 with spectroscopic methods

Star formation began approximately 250 million years after the Big Bang

Future telescopes can observe similar early galaxies

Abstract

A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang. The abundance of star-forming galaxies is known to decline from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we present spectroscopic observations of MACS1149-JD1, a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age. We detect an emission line of doubly ionized oxygen at a redshift of $9.1096\pm0.0006$, with an uncertainty of one standard deviation. This precisely determined redshift indicates that the red rest-frame optical colour arises from a dominant stellar component that formed about 250 million years after the Big Bang, corresponding to a redshift of about 15. Our results indicate the it may be possible to detect such early episodes of star formation in similar galaxies with future telescopes.